Device for picking up pieces of sheet material from a stack of pieces

ABSTRACT

A device for picking up pieces of sheet material from a stack of such pieces which includes a tubular means for piercing a top piece of the sheet material of the stack and for introducing a gaseous medium between that top piece and the next lower piece, and cooperant gripping means for gripping the top piece and lifting same from the stack.

United States Patent 172] Inventor David Oldroyd Rodridge Hall, Hutton Henry Wingate.

Co. Durham. England 1211 Appl No 824.154 [221 Filed May 13, 1969 [45] Patented July 27, I971 [54] DEVICE FOR PICKING UP PIECES OF SHEET MATERIAL FROM A STACK OF PIECES 6 Claims, 4 Drawing Figs.

U.S. Cl 271/26 B6511 3/08 FieldoISearch 271/5, 11,

[561 References Cited UNITED STATES PATENTS 2.454.762 11/1948 Belluche 271/11 2,878,016 3/1959 Russell .1 271/11 3,386,396 6/1968 Jacobs... .Y 271126 X Primary Examiner-Edward A. Sroka Attorneys-Kenwood Ross and Chester E. F lavin ABSTRACT: A device for picking up pieces of sheet material from a stack of such pieces which includes a tubular means for piercing a top piece of the sheet material of the stack and for introducing a gaseous medium between that top piece and the next lower piece, and cooperant gripping means for gripping the top piece and lifting same from the stack PATENTEUJULZYIBYI 3,595,562

SHEET1UF2 INVENTOR.

i I BY ATTORNEYS.

DAV ID OLDROY D DEVICE FOR PICKING UP PIECES OF SHEET MATERIAL FROM A STACK OF PIECES The present invention relates to device for picking up pieces of sheet material from a stack of pieces of sheet material.

BACKGROU ND OF THE INVENTION Three problems often encountered when picking up one or more pieces of sheet material by mechanical means from the top of a stack of pieces are that the piece of material immediately below the piece or pieces required Becomes attachcd to the piece above it and is raised with it, the difficulty of securing a defined number of pieces at the same instant, for example, and also the difficulty of adjusting a device to suit various thicknesses of material and the difficulty of lifting open mesh materials which will not support a conventional vacuum system.

SUMMARY OF THE INVENTION According to the present invention, these problems are overcome by providing adevice for picking up pieces of sheet material from a stack of such pieces, the device comprising means for introducing gas between the top piece or pieces of the stack and the next lower piece, whereby the top piece or pieces can be separated from the next lower piece by introducing gas under pressure directly therebetween, and gripping means for gripping the top piece or pieces and lifting the top piece or pieces off the stack.

A device according to the invention preferably includes tubular means for piercing the upper piece or pieces to enable gas to be introduced directly between the next lower piece and the piece immediately above it.

The device preferably includes two series of teeth, the two series being arranged for cooperation with one another and moveable relative to one another along the direction of the series whereby, when the teeth are placed on a piece of pliable sheet material and relative movement of the two series of teeth is effected, the piece will be caught by the teeth for liftmg up.

Preferably, the teeth are inclined along the direction of movement.

The two series of teeth just described constitute means adapted to be put in connecting relationship with the upper piece of a stack of pieces of pliable sheet material and the device just described can also, optionally, include tubular means for piercing the upper piece of the stack of pieces to enable gas to be introduced between the upper piece or pieces and the next lower pieces.

DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION The two devices according to the invention will now be described by way of example with reference to the accompanying drawings in which:

FIG. I is a side view ofa device according to the invention;

FIG. 2 is a side view similar to FIG. I showing the device in use;

FIG. 3 is a section on the line 33 of FIG. I; and

FIG. 4 is a section through a further device according to the invention.

The device shown in FIGS. I to 3 comprises a support 5 in the form of a square metal plate. A strip of metal 6 is secured to the support 5 by means of two end members 7 and 8 rigid with the strip 6 and which are slotted to leave gaps 9 and II) to accommodate end parts 11 and 12 respectively of a further metal strip 13.

The metal strip I3 can thus slide to-and-fro relative to the strip 6 between the limits imposed by the stops I4 and 15 formed on the strip 13 and which engage the end members 7 and 8 respectively at the limits of movement.

On the strip 6 is formed a series of sharppointed teeth 18 inclined to extend towards the right in FIGS. 1 and 2 and on the strip 13 is formed a series of similar teeth 19 inclined in the opposite direction. In this embodiment, the teeth of each series are located in separate side-by-sidc planes for cooperation with one another and the relative movement of the two series of teeth effected by movement of the strip 13 takes place in the directions in which the series extend. The teeth are also inclined along these directions.

The points of the teeth 18 and 19 extend, as shown, to the same distance just below the lower edge 22 of the support 5 but the distance to which they extend below the support can be adjusted by loosening bolts 23 which secure end members 7 and 8 to the support 5 and sliding the strip 6 up or down as allowed by the slots 24 and 25 in the end members 7 and 8.

The teeth serve to engage in a piece of pliable material to be picked up'and ,the depth of penetration into the material is governed by the distance to which the teeth extend below the support 5.

Also secured to the support 5 is a tubular needle 28 held in a socket member 29 connected to a tube 30 which is bolted to the support by means of a clamp 31 and bolts 32. The sharp point of the needle extends below the edge 22 of the support and below the points of the teeth 18 and 19.

Means (not shown) are provided for shifting the strip 13 toand-fro and for lifting the whole device and shifting it to enable a piece of material which has been picked up to be transported to a desired location. Means (not shown) are also provided for supplying air under pressure along the tube 30 and through the needle 28.

The operation of the device is shown in FIG. 2. The device is placed on top of a stack of pieces 33 of pliable sheet material which is readily pierced by sharp points. The points of the teeth 18 and I9 pierce and extend into the uppermost piece of material, the teeth being at this stage in the relative positions shown in FIG. I. The needle 28 pierces right through the uppermost piece of material.

The strip 13 is then moved to the left in FIGS. 1 and 2 and the teeth 18 and 19 are thus moved apart, each cooperating pair of teeth constituting a now-widened downwardly broadening wedge which makes it difficult for the material to slip off the teeth. The device is now raised and air under pressure is supplied through the needle thus creating a pocket of air under pressure between the uppermost piece of material in the stack and the next lower piece. In this way, the uppermost piece and the next piece are prevented from being picked up together. The piece which has been picked up can now be shifted and dropped where required by returning the teeth to the position shown in FIG. 1 by sliding the strip 13 to the right again.

Both series of teeth can be moveable instead of one only.

The device can be used without the needle 28. The accuracy of location of the teeth points below the support 5 ensures that only the uppermost piece of material is engaged by the teeth and in many cases this is enough to reduce the risk of picking up two pieces of material to an acceptable level.

The teeth 18 and 19 need not be formed on flat plates but can, for example, comprise pins secured on a shaft and biassed or inclined in a similar manner to that shown.

In FIG. 4 is shown another device for picking up pieces of material which can be used for material not susceptible to engagement by pointed teeth.

A vacuum chamber 35 is connected to a device (not shown) for applying suction or air under pressure and has means (not shown) for pressing it down onto a piece of sheet material to be lifted, and means for lifting and transporting the chamber. A needle 36 extends down through the chamber and its point projects below the lower open end 37 of the chamber. The needle is tubular and is connected by a tube 38 to means for supplying air under pressure. For applications of this version the needle tip is sharpened so as to form a circular cutting edge on a plane at right angles to the needle axis, this cutting edge being in contact with the material at all points effectively seals the vacuum chamber from the pressurized air within the needle. The disc of material which is cut out by the needle will be expelled by the air pressure.

The chamber 35 serves for connecting the device to the uppermost piece 38 of the stack of pieces of sheet material by application of suction to the upper surface of the sheet and the needle extends down between the uppermost piece and the next allowing air under pressure to be introduced into this re gion as the uppermost piece is lifted and thus reliably separat ing this piece from the next. This action is assisted by the puckering of the material producing by the suction.

The piece which has been picked up can be deposited by increasing the pressure in the chamber 35, if necessary, above atmospheric pressure.

The needle in the present device is located substantially at the center of the chamber.

This device can be used, for example, for picking up sheets of polyethylene.

In either of the devices described above, two or more tubu-' lar members for introduction of gas between the uppermost piece of the stack and the next lower piece can be provided.

In the device shown in FIGS. 1 and 2, the position of the teeth below the lower surface 22 of the support 5 can be adjusted so that the teeth will pick up two or more pieces of material. The needle 28 will then be arranged to penetrate between the lowermost piece of the number of pieces to be lifted and the next lower piece.

In a further embodiment of the invention, two series of teeth are formed on two concentric cylinders and a support in the form of a further inner concentric cylinder is provided. A tubular needle is mounted on the axis of the cylinders to penetrate one or more pieces of sheet material beneath the device. The teeth on one of the cylinders have their points directed in the opposite direction from the points of the teeth on the other cylinder and the two other cylinders are rotatable in the directions in which their respective teeth are pointed to pick up material. The cylinders can be moved back to release the material. 3

Two or more of the devices described above can be used together if desired on a common mounting to pick up the same piece or pieces of material. For example, four devices may be located one at each corner ofa rectangular sheet.

lclaim:

l. A device for picking up pieces of sheet material from a stack of such pieces and comprising:

tubular means for piercing a top piece of the sheet material of the stack and introducing a gaseous medium between the top piece and the next lower piece, and gripping means for gripping the top piece and lifting the top piece from the stack.

2. A device according to claim 1 wherein the gripping means comprise two series of teeth arranged for cooperation with one another and movable relative to one another along the direction of the series whereby, when the teeth are placed on a piece of material and the series of teeth are moved relative to one another, the piece is gripped by the teeth for a lifting motion.

3. A device according to claim 2 wherein the teeth are inclined along the direction of movement.

4. A device according to claim 2 wherein said teeth of one of said series are inclined oppositely to said teeth of the other of said series.

5. A device according to .claim 1 wherein the gripping means comprises a vacuum chamber having an open end which when placed with the open end resting on the top piece may be evacuated to exert a suction effect on the top piece and thereby grip it for the lifting purpose. 7

6. A device for picking up pieces of sheet material from a stack thereof and comprising: piercing means for piercing a topmost piece of the stack and introducing therethrough a gas into the region between the topmost piece and the next lower piece of the stack, and gripping means for gripping the top piece and lifting'the top piece from the stack. 

1. A device for picking up pieces of sheet material from a stack of such pieces and comprising: tubular means for piercing a top piece of the sheet material of the stack and introducing a gaseous medium between the top piece and the next lower piece, and gripping means for gripping the top piece and lifting the top piece from the stack.
 2. A device according to claim 1 wherein the gripping means comprise two series of teeth arranged for cooperation with one another and movable relative to one another along the direction of the series whereby, when the teeth are placed on a piece of material and the series of teeth are moved relative to one another, the piece is gripped by the teeth for a lifting motion.
 3. A device according to claim 2 wherein the teeth are inclined along the direction of movement.
 4. A device according to claim 2 wherein said teeth of one of said series are inclined oppositely to said teeth of the other of said series.
 5. A device according to claim 1 wherein the gripping means comprises a vacuum chamber having an open end which when placed with the open end resting on the top piece may be evacuated to exert a suction effect on the top piece and thereby grip it for the lifting purpose.
 6. A device for picking up pieces of sheet material from a stack thereof and comprising: piercing means for piercing a topmost piece of the stack and introducing therethrough a gas into the region between the topmost piece and the next lower piece of the stack, and gripping means for gripping the top piece and lifting the top piece from the stack. 